"Rapid and dramatic changes in vegetation" of a small pond on Holy Island (Northumbria): Chaotic dynamics?

This note describes changes to the relative extent of four structurally dominant submerged macrophytes in a pond on Holy Island National Nature Reserve, Northumbria, between 1991 and 1998. The estimated extent of the four submerged macrophytes and bare substratum between 1991 and 1998 showed dramatic changes with no obvious pattern or periodicity, as well as no identifiable natural or anthropogenic causes. Chaotic variation may be an important character of submerged pond plant populations, so that surveys taken in a single year may give an unreliable picture of plant populations.

River Dart fisheries survey 1969

This is the second River Dart Fisheries Survey produced by the Devon River Authority; which was carried out from April to July, 1969. The objective was to examine the distribution and relative abundance of salmonid fish in the River Dart, in order to assess the possibility or desirability, of increasing salmon smolt production of the river by artificial propagation or other means. In addition to the tributaries examined in the 1965 survey, further sections were studied on the River Hems and Holy Brook and reference should be made to the River Survey Report, 1965 for introductory information. The method includes the choice of sections and sampling techniques. The results go through the number/type/class of fishes counted while the survey took place and distribution patterns within the different transects/brooks. The discussion tries to remark the importance of understanding the differences between 1965 and 1969 surveys. The Appendix contains tables with totals of salmonid fish found and distribution sizes for each section, population density tables and a map with new surveyed sections.